Research Of The Space Environment Oriented Delay-Tolerant Networks Routing Technology

Along with the rapid development of space technologies and applications,the research of space network technology is urgently demand. It has become an inexorable trend that the Internet services will expand globally and even to the outer space. Therefore, study on the key technologies used for how to make internet services expand to space has been the research hotspot in related areas in recent years.The environment of space is different from that of land, with the characteristic of high speed movement of spacecraft node, constant change of network topology, long time delay and high bit error rate of transmission and frequent disconnection of communication link, all of which will bring new challenges and demands in network construction. As a result, to support the construction of space network of China, we should propose new network protocols architecture.After analysing the development, characteristic and key technology of space network and Delay-Tolerant Networks(DTN), this paper firstly summarizes the special demands for building networks in the space, and then discusses the fitness and feasibility of the DTN technology for its use in the space. Then, this paper proposes a new space-oriented routing algorithm based on DTN technology—Hybrid Multi-copies Optimal Dijkstrapath (HMOD). By increasing the copy number of same message, the HMOD algorithm can resolve potential failures caused by various reasons and enhance its robustness. Secondly, based on the regular information such as the changing of the network topology and the moving trace of the nodes, the HMOD can calculate the optimal path and transmit message along the path to realize the fast transmission. Finally, by flooding the "delete-acknowledgement" in the network, the algorithm can clean away redundant message copies timely. To enhance the performance of HMOD under congestion networks, we also proposed a new buffer management strategy based on the priority of messages. When the network is congested, the HMOD can discard messages selectively according to the strategy.The paper establishes simulation scenarios using the ONE simulator and validates the performance of the HMOD algorithm by changing simulation parameters such as bandwidth, buffer, size of message, simulation time and TTL of message. Also, this paper makes comparison with Epidemic, Spray and Wait and PRoPHET, which are three representative algorithms in DTN. The simulation results demonstrate that the HMOD can achieve 10%-30% increment over Spray and Wait and 30%-50% increment over Epidemic and PRoPHET in delivery-ratio. Also, the HMOD reduces the average latency of messages by 10% compared with Spray and Wait, The similation results also demonstrate that the overhead-ratio of transferring message of HMOD is only 10% or even 1% of of Epidemic and PRoPHET. Finally, we summarize the paper and point out the future works.